Small speakers, such as are used in head sets, especially of the type used in portable audio devices, such as audio players, cell phones, and in some cases in security head sets, and military systems, and possibly also in hearing aids, are of compact minimal size, for obvious reasons.
As a result, even though the audio quality of the actual signal may be adequate, the quality of the audio sound delivered by the speakers is often much less than is desirable. This is partly due to the limitations imposed in the design by the small size of the speakers themselves.
However it is found that much of the loss of quality is due to noise induced in the speaker circuits. If this induced noise can be eliminated then the audio quality of the sound from the speakers will be both much higher, and of greater clarity.
The signals may come from sources such as tape, CD, or memory chip, or may be communication signals such as mobile phones, radio communication, or possibly hearing aids.
The audio signals are usually stereo sound signals. These stereo signals are supplied as left and right hand signals. Both include what can be broadly described as combining both high, medium, and low frequencies. Circuits usually provided in such speakers this purpose are usually miniature in scale and somewhat primitive. The speakers themselves also incorporate speaker coils, and they are believed to contribute to the electronic noise.
In prior U.S. Pat. Nos. 5,615,272, and 5,519,781 and Canadian Patent 2,192,163 . . . . Inventor V. W Kukurudza, there are disclosed noise suppression circuits incorporating special “bifilar” wound coils. These bifilar coils actually comprise two coils in one. A pair of such bifilar coils is preferably used in each noise suppression circuit. The bifilar coils produce a substantial reduction in electronic noise in the circuit. The bifilar coils also help to reduce the electronic noise originating in the speaker coils themselves. However when it is attempted to provide a miniaturised noise suppression circuit with such bifilar coils, of an extremely compact size, for use in the type of head sets or speaker systems described above, numerous other problems arise.
The bifilar coils develop significant internal stresses during operation. The coils must be secured so as to withstand these stresses. Not only must the bifilar coils be securely mounted, but also they must be maintained in spaced apart relation, so as to avoid magnetic coupling between the one pair of bifilar coils and the other pair.
The bifilar coils also must be supported in such a way that any heat can be dissipated, without affecting either the bifilar coils or the circuit board, or the head set system, and without impairing the performance of the bifilar coils themselves.